Hydrocephalus

Hydrocephalus is an abnormal buildup of cerebrospinal fluid (CSF) in the ventricles of the brain. The fluid is often under increased pressure and can compress and damage the brain. Hydrocephalus can arise before birth or any time afterward. It may be due to many causes including a birth defect, hemorrhage into the brain, infection, meningitis, tumor, or head injury. Most forms of hydrocephalus are the result of obstructed CSF flow in the ventricular system. With birth defects, physical obstruction of CSF flow in the ventricular system is usually the cause of the hydrocephalus. Hydrocephalus is a common companion of spina bifida (meningomyelocele). What is termed "hydrocephalus ex-vacuo" occurs when there is damage to the brain caused by stroke or injury, and there may be an actual shrinkage of brain substance. "Hydrocephalus ex-vacuo" is essentially only hydrocephalus by default; the CSF pressure itself is normal. Normal pressure hydrocephalus (NPH) can also occur due to a gradual blockage of the CSF drainage pathways in the brain. Although the ventricles enlarge, the pressure of the CSF remains within normal range. NPH is characterized by memory loss (dementia), gait disorder, {{}}urinary incontinence and a general slowing of activity. In old age or persons with Alzheimer's disease, the entire brain may shrink and the CSF fills up the space created by the shrinkage. This is not due to hydrocephalus. The diagnostic signs and symptoms of hydrocephalus depend upon the age of the person: In infants the most obvious sign of hydrocephalus is usually an abnormally large head. (That is one reason a baby's head should be measured at every well-baby visit). Symptoms of hydrocephalus in an infant may include vomiting, sleepiness, irritability, an inability to look upwards, and seizures. In older children and adults there is no head enlargement from hydrocephalus, but symptoms may include headache, nausea, vomiting and, sometimes, blurred vision. There may be problems with balance, delayed development in walking or talking, and poor coordination. Irritability, fatigue, seizures, and personality changes such as an inability to concentrate or remember things may also develop. Drowsiness and double vision are common symptoms as hydrocephalus progresses. Treatment of hydrocephalus involves the insertion of a shunt to let the excess fluid exit and relieve the pressure on the brain. The shunt is a flexible, plastic tube with a oneway valve. The shunt is inserted into the ventricular system of the brain to divert the flow of CSF into another area of the body, where the CSF can drain and be absorbed into the bloodstream. The prognosis (outlook) with hydrocephalus depends the cause and the timing of the diagnosis and treatment. Many children treated for hydrocephalus are able to lead normal lives with few, if any, limitations. In some cases, cognitive impairments in language and non-language functions may occur. Problems with shunts such as infection or malfunction require revision of the shunt. Hydrocephalus is sometime called "water on the brain." The word "hydrocephalus" in Greek literally means "watery head."

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A condition marked by an excessive accumulation of cerebrospinal fluid resulting in dilation of the cerebral ventricles and raised intracranial pressure; may also result in enlargement of the cranium and atrophy of the brain. SYN: hydrocephaly. [hydro- + G. kephale, head]

- communicating h. type of h. in which there is an abnormality in cerebrospinal fluid absorption; there is no obstruction to cerebrospinal fluid flow in the ventricular system or where the cerebrospinal fluid passes into the spinal canal.

- congenital h. h. due to a developmental defect of the brain. SYN: primary h..

- double compartment h. independent supra- and infratentorial h. usually due to a veil occlusion of the aqueduct of Sylvius.

- external h. 1. accumulation of fluid in the subarachnoid spaces of the brain; 2. accumulation of fluid in the subdural space owing to a persistent communication between the subarachnoid and subdural spaces.

- h. ex vacuo h. due to loss or atrophy of brain tissue; less commonly associated with raised intracranial pressure.

- internal h. h. in which the accumulation of fluid is confined to the ventricles.

- noncommunicating h. SYN: obstructive h..

- normal pressure h. a type of h. developing usually in older people, due to failure of cerebrospinal fluid to be absorbed by the pacchionian granulations, and characterized clinically by progressive dementia, unsteady gait, urinary incontinence, and usually, a normal spinal fluid pressure. SYN: occult h..

- obstructive h. h. secondary to a block in cerebrospinal fluid flow in the ventricular system or between the ventricular system and spinal canal. SYN: noncommunicating h..

- occult h. SYN: normal pressure h..

- otitic h. a form of h. associated with otitis media and thrombosis of one or both sigmoid sinuses of the dura, characterized by marked increase in cerebrospinal fluid pressure.

- postmeningitic h. ventricular dilation following meningitis and secondary to obstruction of cerebrospinal fluid pathways.

- posttraumatic h. ventricular dilation following injury, due either to impaired circulation and/or absorption of cerebrospinal fluid or due to loss of brain substance (h. ex vacuo).

- primary h. SYN: congenital h..

- secondary h. an accumulation of fluid in the cranial cavity, due to meningitis or obstruction to the venous flow.

- thrombotic h. increase in cerebrospinal fluid and of intracranial pressure following thrombosis of the cerebral veins or sinuses; caused by septic infection, dehydration, tuberculosis, typhoid, leukemia, and other conditions.

- toxic h. thrombotic h. associated with some general infection or toxic state.

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hy·dro·ceph·a·lus -'sef-ə-ləs, Brit also -'kef- n, pl -li -.lī an abnormal increase in the amount of cerebrospinal fluid within the cranial cavity that is accompanied by expansion of the cerebral ventricles, enlargement of the skull and esp. the forehead, and atrophy of the brain

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n.

an abnormal increase in the amount of cerebrospinal fluid within the ventricles of the brain. In childhood, before the sutures of the skull have fused, hydrocephalus makes the head enlarge. In adults, because of the unyielding nature of the skull, hydrocephalus raises the intracranial pressure with consequent drowsiness and vomiting. Hydrocephalus may be caused by obstruction to the outflow of cerebrospinal fluid from the ventricles or a failure of its reabsorption into the cerebral sinuses. spina bifida may be associated with hydrocephalus in childhood. Treatment involves treating the underlying cause and, if necessary, diverting the excess cerebrospinal fluid into the abdominal cavity, where it is absorbed. This is achieved by tunnelling a thin tube from the ventricles to the abdomen (ventriculo-peritoneal shunt) or atrium (ventriculo-atrial shunt).

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hy·dro·ceph·a·lus (hi″dro-sefґə-ləs) [hydro- + -cephalus] a condition marked by dilatation of the cerebral ventricles, most often occurring secondary to obstruction of the cerebrospinal fluid pathways (see ventricular block, under block), and accompanied by an accumulation of cerebrospinal fluid within the skull; the fluid is usually under increased pressure, but occasionally may be normal or nearly so. In children it may occur prior to closure of the skull sutures and is typically characterized by enlargement of the head, prominence of the forehead, brain atrophy, mental deterioration, and convulsions. In adults the syndrome includes incontinence, imbalance, and dementia. It may be congenital or acquired and may be of sudden onset (acute h.) or be slowly progressive (chronic or primary h.). Called also hydrocephaly, hydrencephaly, and hydrencephalus. hydrocephalic adj